Action delegate type in C Sharp (C#) - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is an Action delegate in C#?

An Action delegate is a predefined delegate type in C# that represents a method that returns void and can take zero or more input parameters.

beginner

How many parameters can an Action delegate have?

An Action delegate can have from zero up to 16 input parameters, but it always returns void (no return value).

beginner

Write a simple example of an Action delegate that takes no parameters.

Action greet = () => Console.WriteLine("Hello!"); greet(); // Prints "Hello!"

intermediate

What is the difference between Action and Func delegates?

Action delegates always return void, while Func delegates return a value and can have input parameters.

beginner

How do you declare an Action delegate that takes two integers and prints their sum?

Action printSum = (a, b) => Console.WriteLine(a + b); printSum(3, 4); // Prints 7

What does an Action delegate return?

A void

B int

C string

D bool

Action delegates always return void, meaning they do not return any value.

Which of the following is a valid Action delegate declaration?

A Action<int> myFunc;

B Func<void> myAction;

C Func<int, string> myAction;

D Action<int, string> myAction;

Action is valid because Action can take parameters and returns void.

How many parameters can an Action delegate have at most?

A 16

B 8

C 4

D No limit

Action delegates can have up to 16 input parameters.

Which delegate type should you use if you want a method that returns a value?

A Action

B EventHandler

C Func

D Predicate

Func delegates return a value, unlike Action which returns void.

What is the output of this code? Action<string> print = s => Console.WriteLine(s); print("Hi");

A print

B Hi

C s

D No output

The Action delegate prints the string passed to it, so it outputs "Hi".

Explain what an Action delegate is and how it differs from a Func delegate.

Think about return types and input parameters.

Write a simple example of an Action delegate that takes two integers and prints their product.

Use Action<int, int> and a lambda that multiplies and prints.